This invention relates broadly to flexible bearings, and more specifically to bearings that are constructed of alternate layers of elastomer and rigid materials, stacked and bonded together; so that they are flexible in directions parallel to the layers, but are relatively unyielding in directions perpendicular thereto. This invention described herein was made during the course of or under Contract Number N0003072C0108 with the U.S. Navy.
The type of flexible bearing comprising alternate layers of rigid material and elastomer has many uses, including applications to motor mounts and bridge abutments. More recently, it has been found to be useful for mounting a movable thrust nozzle to a rocket, so that the nozzle may be rotated from side to side for steering the rocket. A typical arrangement of the bearing for this use is shown in FIG. 3 of U.S. Pat. No. 3,429,622 to R. E. Lee, et al, wherein the bearing is labeled "10."
Other U.S. Pats. showing this type of flexible bearing are Nos. 3,390,899 to J. T. Herbert, et al; 3,504,902 and 3,504, 903 to A. S. Irwin; and 3,504,904 to A. S. Irwin, et al.
Although this type of bearing functions very well for the above purpose, it has been found that the layers of elastomer tend to act as springs that resist the torques exerted on the bearing by the nozzle actuators (usually hydraulic cylinders, each attached at one end to the rocket nozzle and at the other end to the rocket case). These layers of elastomer tend to maintain the thrust nozzle in a position of alignment with the axis of the rocket and to resist side forces thereon in accordance with Hooke's Law, i.e. the resistance increases with the angular distance of the nozzle from its axial alignment. This resistance necessitates the use of larger, heavier, more powerful actuators than certain other means of mounting the nozzle require.